What made that quake significant was the duration (it went on for 15 seconds). That's a factor that supersedes the strength of the quake to an extent. Because a weaker quake will cause more damage over a long period of time.
Put it this way: Hit a wall with a hammer and you might cause a dent. Continually hit that wall with a hammer for 15 seconds and you'll probably break through.
The 2001 earthquake in Gujarat lasted for more than 2 minutes and killed around 20,000 people. The quake struck early in the morning during India's Republic day celebrations. The authorities said that the long duration caused more damage http://en.wikipedia.org/wiki/2001_Gujarat_earthquake
And when: the 7.1 struck about 4:30am Saturday morning--the outcome would've been very different if it had also struck at ~12:50pm weekday as the 6.3 did.
A 9.2 is 2.5 gigatons.